Entomology & forage
The insects and forage fish eat, and the stages they pass through. Knowing what is hatching, and what stage it is in, is most of the answer to what fly to use.
37 terms in 6 groups
Aquatic insects (7)
- Caddisflyalso Caddis, Sedge, Sedge flyA caddisfly is a common freshwater insect that trout and other fish eat in its larva, pupa, and adult stages. Many species live in streams and rivers, and their hatches can drive steady feeding.
- Craneflyalso Crane fly, Crane-flyA cranefly is a long-legged fly whose larvae live in wet soil, stream edges, or slow water. The larva is a common food item for trout in some waters.
- Damselflyalso Damsel, Damselfly nymphA damselfly is an odonate insect whose juvenile stage lives in water and is a common food source for trout, bass, and panfish, especially in lakes and slow water.
- Dragonflyalso Dragonfly nymphA dragonfly is a large predatory insect. Trout and bass eat the underwater nymph stage, and bass sometimes take the adults.
- Mayflyalso Ephemeroptera, mayfliesA mayfly is a freshwater insect with aquatic nymph stages that trout and other fish eat in every stage of its life cycle, from nymph to dun to spinner.
- Midgealso Chironomid, Midge flyA midge is a small two-winged fly; in fly fishing it often means a chironomid. Most of their larvae and pupae live in water. Midges hatch in every month on many rivers and lakes, and trout eat them year-round.
- Stoneflyalso Stonefly nymph, PlecopteraStoneflies are aquatic insects whose young live mostly in moving water and whose nymphs crawl out to emerge. They are an important trout food, especially where big species like salmonflies and golden stones are present.
Baitfish (7)
- Baitfishalso forage fish, minnowSmall forage fish that predators eat, like minnows, shad, smelt, and mullet. In fly fishing, “baitfish” also means the food source a streamer is meant to imitate.
- Dacealso Common dace, Dace minnowDace are slim minnows that live in rivers and streams. They are common prey for trout and other freshwater predators.
- Glass minnowalso glass minnows, glass minnow flyA “glass minnow” is a small, nearly transparent baitfish common in saltwater. In fly fishing, it also means any slim, see-through minnow imitation meant to match that look.
- Mulletalso Grey mullet, Striped mullet, Finger mulletMullet are common coastal baitfish that travel in schools over flats, beaches, and estuaries. They are a major food source for predators like snook, tarpon, and striped bass.
- Sculpinalso Sculpin baitfish, Freshwater sculpin, Sculpin patternA sculpin is a small bottom-dwelling fish with a wide head and big pectoral fins. Trout and bass eat them, and many streamers are tied to imitate their shape and movement.
- Shineralso shiners, shiner minnow“Shiner” is a common name for several silvery minnows that live in freshwater and get eaten by trout, bass, pike, and other predators.
- Smeltalso Rainbow smeltSmelt are slender, schooling baitfish that live in cold freshwater and anadromous systems. They are a key forage for trout, salmon, and lake trout in many lakes and some rivers.
Crustaceans & worms (6)
- Crabalso crab fly, crab patternA crab is a hard-shelled crustacean that lives on flats, beaches, and mangrove edges. Many saltwater gamefish key on crabs, so crab patterns are a standard part of flats fishing.
- Crayfishalso Crawdad, CrawfishA crayfish is a freshwater crustacean that looks like a small lobster. Trout, bass, and carp eat them, and many streamers are tied to imitate their shape and movement.
- Leechalso Leech pattern, Leech flyA leech is a freshwater worm-like invertebrate that swims with an undulating motion and lives in lakes, ponds, and slow river edges. Fly patterns that imitate leeches are usually fished subsurface.
- Scudalso Freshwater shrimp, AmphipodA scud is a small freshwater crustacean, usually a side-swimming amphipod. Trout and other fish eat them year-round, especially in spring creeks, tailwaters, and lakes.
- Shrimpalso shrimp pattern, shrimp flyShrimp are small crustaceans that many flats and inshore fish eat. “Shrimp” also refers to fly patterns tied to imitate their shape, color, and quick darting movement.
- Sowbugalso Freshwater sowbug, Sow bugA sowbug is a small freshwater crustacean, similar to a scud, that trout eat year-round where it’s abundant.
Life stages (5)
- Dunalso Mayfly dun, SubimagoA dun is the newly emerged, winged subimago stage of a mayfly, right after it leaves the water and before it becomes a spinner.
- Hatchalso Insect hatch, Bug hatchA hatch is a period when aquatic insects emerge in numbers, often bringing trout into a steady feeding rhythm.
- Larvaalso Insect larva, Midge larva, Caddis larvaAn aquatic insect’s immature stage for insects with complete metamorphosis, like midges and caddisflies.
- Pupaalso Pupae, Pupal stageA pupa is the in-between life stage where some aquatic insects transform from larva to adult. In trout fishing, “pupa” usually points to caddisflies and midges as they rise toward the surface to emerge.
- Spinner fallalso Mayfly spinner fallA spinner fall is when adult mayflies return to the water to lay eggs, and many end up dying and drifting downstream.
Mayfly hatches (8)
- Blue-winged olivealso BWO, Baetis, Blue wing olive, Blue-wing olive“Blue-winged olive” (BWO) is the common fly-fishing name for several small mayflies in the Baetis group. Anglers use it to describe the hatch and the flies used to match it.
- Green drakealso Green Drake, Green drake hatch, Green drakesA “green drake” is a large mayfly hatch that can bring trout to the surface for big dry flies, especially in late spring and early summer. The name is used for several similar-looking mayfly species depending on the region.
- Hendricksonalso Ephemerella subvaria, Red Quill, Hendrickson hatchA Hendrickson is a spring mayfly hatch best known on Eastern trout rivers. Anglers use the name for the insects and for fly patterns that match their duns and spinners.
- Hexageniaalso Hex, Hex hatchHexagenia are large burrowing mayflies (the “hex” hatch). Their nymphs live in soft-bottom lakes and slow rivers, and the adults can bring big trout up to feed after dark.
- March brownalso March Browns, March Brown hatch“March brown” is a common name for several medium-to-large spring mayflies and the hatch events tied to them. The name can mean different species depending on region.
- Pale morning dunalso PMD, Pale Morning DunsA “Pale Morning Dun” (PMD) is a common mayfly hatch made up of small, pale yellow mayflies. Anglers use PMD nymph, emerger, dun, and spinner patterns to match it.
- Sulphuralso Sulfur, Sulphur hatch, Sulfur hatch, Ephemerella sulphur“Sulphur” is a common hatch label for small yellow mayflies, most often in the genus Ephemerella. Anglers use it to match pale yellow duns and their evening spinner falls on many trout rivers.
- Tricoalso Tricorythodes, Trico hatch, Trico spinner fallTrico is a tiny mayfly (genus Tricorythodes) best known for dense summer morning hatches and spinner falls. On many trout rivers it brings selective fish and fine-tippet dry-fly fishing.
Stonefly & caddis hatches (4)
- Golden stonealso Golden stones, Golden stonefly, Golden stone hatch, Golden stone nymphA “golden stone” is a common name for medium-to-large yellow to golden stoneflies, and the hatch anglers watch for when those adults are on the banks and fluttering on the surface.
- October caddisalso October Caddis, Fall caddisOctober caddis is a large, orange fall caddisfly hatch, best known on Western trout rivers where adults flutter along banks and skitter on the surface.
- Salmonflyalso Pteronarcys, Pteronarcys californica, Giant stoneflyA salmonfly is a very large stonefly, best known for its late-spring to early-summer adult hatch on many Western rivers and the oversized dry flies it inspires.
- Yellow Sallyalso Little Yellow Stonefly, Yellow Stonefly, Yellow Sally hatchA “Yellow Sally” is a small yellow stonefly, and the name anglers use for the hatch and the flies that imitate it.